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A003641 Number of genera of quadratic field with discriminant -4n+1.
(Formerly M0061)
1
1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 2, 2, 1, 4, 1, 2, 1, 2, 2, 1, 1, 4, 2, 1, 2, 1, 4, 2, 1, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 2, 4, 2, 2, 2, 2, 1, 2, 1, 4, 1, 1, 2, 2, 4, 1, 1, 2, 1, 4, 1, 1, 1, 1, 2 (list; graph; refs; listen; history; internal format)
OFFSET

1,4

REFERENCES

D. A. Buell, Binary Quadratic Forms. Springer-Verlag, NY, 1989, pp. 224-241.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Index entries for sequences related to quadratic fields

CROSSREFS

Cf. A003642.

Sequence in context: A185102 A050377 A001826 * A165190 A025890 A043277

Adjacent sequences:  A003638 A003639 A003640 * A003642 A003643 A003644

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein

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Last modified February 16 17:48 EST 2012. Contains 205939 sequences.